Color picture tube of shadow mask type with particular faceplate panel structure

Abstract

A color picture tube of shadow mask type includes a faceplate panel mounted on the tube. The faceplate panel has curvatures along its major and minor axes, respectively. When the outer surface contour of the faceplate panel is represented by a three-dimensional expression in the orthogonal coordinate system defined by the X-axis corresponding to the major axis, the Y-axis corresponding to minor axis, and the Z-axis corresponding to the axis of the tube, respectively, curved contours Z x and Z y of the faceplate panel along the major axis and the minor axis are so realized as to be approximated by Z x A 1 X 2 +A 2 X 4 and Z y =A 3 Y 2 +A 4 Y 4 , respecvtively, where X and Y represent distances from the center of the faceplate panel along the X-axis and the Y-axis, respectively, and wherein the constants A 1 , A 2 , A 3 and A 4 are so selected that the conditions that 0.3≦P x (X=X 1 )≦0.6 and 0.95≦P y (Y=Y 2 )≦1.0 where P x =A 1 X 2 /(A 1 X 2 +A 2 X 4 ), P y =A 3 Y 2 /(A 3 Y 2 +A 4 Y 4 ) are satisfied at points X 1 and Y 2 on the boundaries defining an effective picture area on the faceplate. Further, the contours of the effective picture area defining boundaries extending in parallel with short and long sides of the outer surface of the faceplate panel are so curved as to have approximately equal curvature, the radius R (mm) of which on the boundary is so selected as to satisfy the condition that 1.5 (42.5 V+45.0)≦R≦2.0 (42.5 V+45.0), where V represents the diagonal length of the effective picture area.

We claim: 
     
       1. A color picture tube of shadow mask type, including a faceplate panel mounted on said tube, said faceplate panel having curvatures along its major and minor axes; wherein when outer surface contour of said faceplate panel is represented by a three-dimensional expression of a space defined by X-axis corresponding to said major axis, Y-axis corresponding to said minor axis and Z-axis corresponding to the axis of said tube, respectively, contour Zx of said panel along said major axis is so implemented as to be approximated by Zx=A 1  X 2  +A 2  X 4  and contour Zy of said panel along said minor axis is so implemented as to be approximated by Zy=A 3  Y 2  +A 4  Y 4 , where X and Y represent distances from the center of said faceplate panel along said X-axis and said Y-axis, respectively, and Zx and Zy represent distances of said outer surface contour of said faceplate panel along said X-axis and Y-axis from the center of said panel to Z-axis direction, respectively, and where constant A 1  and A 2   are so selected such that a condition 0.3≦Px(X=X 1 )≦0.6 where Px=A 1  X 2  /(A 1  X 2  +A 2  X 4 ) is satisfied at a point X=X 1  and Y=0 which is on boundary defining an effective picture area on said faceplate and constants A 3  and A 4  are so selected such that a condition 0.95≦Py (Y=Y 2 )≦1.0 where Py=A 3  Y 2  /(A 3  Y 2  +A 4  Y 4 ) is satisfied at a point X=0 and Y=Y 2  which is on boundary defining an effective picture area on said faceplate; and   wherein the contours of said effective picture are defining boundaries extending in parallel with short and long sides of the outer surface of said faceplate panel are so curved as to have an approximately same curvature, the radius R(mm) of said curvature at said boundary being so selected as to satisfy the condition that 1.5 (42.5 V+45.0) ≦R≦2.0 (42.5 V+45.0) where V represents the diagonal length (inch) of said effective picture area.   
     
     
       2. A color picture tube according to claim 1, including a shadow mask mounted within said tube, said shadow mask having a substantially same configuration as that of said faceplate panel. 
     
     
       3. A color picture tube according to claim 1, wherein said faceplate panel has curvatures along its major and minor axes, which curvatures differ from each other. 
     
     
       4. A color picture tube according to claim 1, wherein the curvature along the effective picture area defining boundary extending in parallel with said major axis is smaller than the curvature along the effective picture area defining boundary extending in parallel with said minor axis. 
     
     
       5. A color picture tube according to claim 1, wherein the curvature in each of planes parallel to the minor axis is greater at the side of said panel than near the major axis thereof.